Cesarean Incisions in Women of Size: Supraumbilical?

Illustration used with permission © Anatomy by Design, Inc.

We previously discussed cesarean incision choice in women of size ─ specifically, the choice of vertical (up-down) incisions vs. low transverse (side-to-side) incisions.

The gist of those posts is that for years many doctors were erroneously taught that a vertical (up-down) incision was best in very fat women.  They were taught that the area under a fat woman's belly (called an "apron", "pannus" or "panniculus") was far too prone to infection, so it was best not to do an incision there.  Instead, many were taught to do a vertical skin incision, which often turned into a vertical or "classical" incision on the uterus as well.

High-BMI women were told that this vertical incision would lessen their risk for complications like wound infection, wound separation, bleeding, etc., but when researchers finally got around to actually studying this, they found the opposite ─ that outcomes were not improved with vertical incisions, that vertical incisions actually worsen outcomes in many cases.  Furthermore, classical uterine incisions have poorer outcomes, both short-term and long-term, and therefore should not be undertaken lightly.

Despite the evidence that vertical incisions do not improve outcome and may worsen it, many doctors are still promoting the idea that an incision under the belly is far too prone to infection to use.  As recently as 2006, one OB-GYN wrote, "In general, there is a lot to be said for an incision not buried under the pannus of fat, so that fresh air can help keep the wound dry."  And the illustration above is from a 2009 article, which also highlights the supposed dangers of an incision under the belly.

Now some doctors are promoting another choice for cesarean incisions in very heavy women ─ one done above or near the belly button. This is called a "supraumbilical" (above the belly button) incision.  This incision is not new, but is gaining new traction among some OBs. While not extremely common, it is being promoted by some doctors as beneficial in supersized women.  But is it?

So today, let's talk about supraumbilical incisions and their pros and cons.

Trigger Alert - This post discusses the difficulties associated with surgery on the bellies of very fat women.  Some graphic details are included, and the tone of the research cited is often quite judgmental.  Therefore, readers who might find this triggering may wish to skip this post.

Supraumbilical vs. Low Transverse Incisions

The difficulty in doing abdominal surgery on very heavy women is the barrier that a large amount of belly fat presents.  If you cut through the middle of the belly, you are going through the thickest part of the belly, which takes longer, increases the risk for excessive bleeding, and inhibits healing because of decreased vascularization of adipose (fat) tissue.

Thus, surgeons have come up with 2 approaches to avoiding incisions in the fattest part of the belly. The first is a low transverse incision, under the belly, and the second is a supraumbilical incision, above or near the belly button (umbilicus).

The low transverse incision (usually Pfannenstiel or Joel-Cohen) has repeatedly been shown to have superior outcomes to other incisions, even in obese women.  However, doing it in women with very large bellies is not easy.

Low-transverse incision made under the belly
by pulling back the panniculus

In the picture just above, the woman's overhanging belly is pulled back via a strap or tape towards the mother's head.  This exposes the area under the panniculus (which tends to be thinner) and a low transverse (side-to-side) incision is made there.

Again, many doctors have erroneously been taught that this area is hot, moist, and "a veritable bacteriologic cesspool" (yes, actual quote from the medical literature) and thus highly prone to infection.  In addition, an assistant is sometimes required to hold back the belly during a cesarean, and this can be very physically tiring.  Therefore, some doctors have sought an alternative.

The supraumbilical incision has become popular in some obstetric circles as a possible alternative, especially for women with extremely large or "droopy" bellies.

The $64,000 question is whether this improves outcomes over low-transverse incisions.

Types of Supraumbilical Incisions

In most women, a supraumbilical skin incision translates to a vertical (up-and-down) incision in the skin above the belly button, as in the picture below (repeated from the top of the post). This then is usually accompanied by a vertical/classical incision in the uterus underneath.



This differs from the usual classical incision, which is a vertical (up-down) incision also , but done from the belly button down to the pubic bone.  This also involves a uterine incision in the upper segment of the uterus.

The main difference between a supraumbilical incision and the usual classical incision is that the supraumbilical is done above the belly button, not below it.

Sometimes a supraumbilical incision is done side-to-side (transverse above the belly button, on the upper uterine segment), a picture of which can be found here. 

However, in a few women with extremely voluminous and droopy bellies, a skin incision above the belly button translates into an incision into the lower segment of the uterus, as in the picture below.

A supraumbilical skin incision,
but with a low uterine incision

[Sorry for the blurry image above; it is from a medical study and is very small. When enlarged, the text becomes blurry.  The words from L to R are "panniculus", "umbilicus", "projection of the pubic symphysis", "abdominal and low uterine segment incisions".]

In other words, in a few women the belly droops down low enough that it pulls down the alignment of the skin over the uterus, so that the skin area above the belly button sits near the the pubic bone (pubic symphysis), over the lower uterine segment instead.  In such a case, a supraumbilical skin incision can translate into a low transverse uterine incision. Since lower-uterine segment (LUS) incisions have fewer complications, this combines the advantages of easier surgical access with a supraumbilical skin incision and the better long-term prognosis of a LUS uterine incision.

However, most of the time, a supraumbilical skin incision means a uterine incision in the upper uterus, which carries more risks, both short-term and long-term.  

Patterson (2002) and Bakhshi (2010) compared outcomes in women who had classical incisions vs. low transverse incisions.  They found that women with classical incisions had more infections, more hysterectomies, more blood transfusions, longer operating time, and more intensive care admissions.  They also had far more uterine scar separations in future pregnancies.  Therefore the decision to do a supraumbilical incision potentially has far-reaching implications.

Some doctors are far too quick to resort to supraumbilical incisions on "morbidly obese" women, and at BMIs that don't truly require it. Since most supraumbilical incisions result in classical uterine incisions, doctors are putting these women at considerable risk, whether it's because they don't want to deal with the mechanical challenges of a low transverse incision, or because they have erroneously been taught that the risk of infection is higher in an under-the-belly incision.

Cosmetic Considerations

Another problem with supraumbilical incision that scarring that accompanies it.

The negative cosmetic and psychological impact of a giant scar above the belly button in women of size must not be underestimated.

Research on supraumbilical incisions never considers this, as if the surgeons believe that the bellies of women of size are already so repugnant that a giant scar in the middle of the belly is of no consequence.  Yet, as with midline vertical incisions, the potential psychological impact of such a disfiguring scar is tremendous.

I have a friend who had multiple cesareans ─ not because she wanted them but because of the fat-phobic ignorance of her first OB.  That OB had been taught that a low transverse incision was too prone to infection in obese women, so her first cesarean was supraumbilical, with a classical vertical incision on the uterus. Her next two cesareans were low-transverse repeat cesareans with a different OB, since she could not find anyone who would  let her try a VBAC with a prior classical incision. Her subsequent OB was very frank that the decision to do a supraumbilical incision was totally unnecessary in her first cesarean, and very sympathetic to her frustration that this arbitrary decision by the first OB had totally taken away all her options in subsequent pregnancies.

Even as time lessened the scarring, she found the supraumbilical scar far more disfiguring than her low transverse scars.  She wrote:

I had a supraumbilical incision, so I have this huge scar about 1 inch wide in the middle of my abdomen.  Not very pretty.... 

As far as cosmetics go, my LT [low transverse] incision is so far down it starts right above my pubic hairline...so it's barely noticeable, and in an area no one else but [my husband] would see.

The scarring from a supraumbilical incision is noticeable, and it does matter to women of size.  Just because their bellies are large doesn't mean that cosmetic considerations are irrelevant.

Oh, and those subsequent low-transverse incisions my friend had?  No infection issues at all, despite what her first OB was taught.  But the psychological impact of that first, supraumbilical scar has stayed with her for years. And the doctor's choice for a supraumbilical incision denied her any choices in her future births, any chance at a VBAC, and exposed her to the risks of classical cesareans, not to mention the risks of the subsequent repeat cesareans that were mandatory with the doctors in her area.

The cosmetic considerations of such a disfiguring scar in such an easily-seen place should not be underestimated when making the decision about incisions in women of size.  Just because a woman is obese doesn't mean these cosmetic considerations are moot.  Nor should the limitations supraumbilical incisions place on future pregnancies be shrugged off lightly.

Supraumbilical Incisions: A Summary

To be fair, supraumbilical incisions have certain advantages from the surgeon's point of view. They offer easier accessibility to the uterus in women with very large amounts of belly fat.  They are also less demanding on the O.R. staff, who often have to "pull back" and hold the pannus away from the lower uterine segment, which can be difficult and tiring. One can appreciate and sympathize with the technical demands of doing abdominal surgery in heavy women.

However, given the downsides of supraumbilical scars, this is not enough.  Supraumbilical incisions need to be shown to result in clinically superior outcomes, and they have not been.  Although researchers expected that supraumbilical incisions would improve outcome in very fat women, the data showed that they did NOT actually improve outcome.  Outcomes were actually similar among women with low transverse incisions and supraumbilical incisions.

Again, most of these supraumbilical incisions result in uterine incisions in the upper uterine segment, which is MUCH more risky, much  harder to recover from, and which has profound implications for any future pregnancies.  It also essentially ensures the woman must always have repeat cesareans in the future. Furthermore, they leave a large, very disfiguring scar on the upper abdomen of women after the surgery is over.  A low transverse skin incision is also scarring, but is far less obvious and far less disfiguring in most cases.

The whole premise of doing supraumbilical incisions was to improve outcome for obese women. If they do not improve outcome while simultaneously placing the woman at extra risk and being quite disfiguring, there is no good reason for doing supraumbilical incisions in most cases.

Yes, supraumbilical incisions are easier to perform and are easier on the operating room staff.  Yes, low transverse incisions are harder in supersized women and can present many technical and physical challenges.  However, the bottom line is that the surgeon's convenience should take a back seat to the best interests of the mother and baby (and future babies).

Of course, there may occasionally be situations where such an incision might be useful, such as in a woman with extreme obesity, a woman with an extremely large and droopy belly, or a woman with a complicated placenta previa (low-lying placenta).  No one is saying that supraumbilical incisions should be absolutely banned, only that they should be kept for very rare cases where they are truly needed.  They should not be done routinely, even in high-BMI women.

Fortunately, most cesareans being done today are low-transverse incisions, even in women of size.  However, there are some doctors who use classical or supraumbilical incisions as a routine alternative to low transverse incisions in "morbidly obese" women, and their threshold for using it is far too low in some cases.  The mean BMI for a supraumbilical incision in the Tixier study below was 47, which is near my own BMI.  Many women of this BMI (including me) and a lot larger have had low transverse incisions with no problems, so any routine use of supraumbilical incisions in this size is highly questionable.

A supraumbilical incision can be a useful tool under certain extreme circumstances.  It's worth documenting the technique for that reason. Even so, it must be pointed out that supraumbilical incisions do not improve outcome over low transverse incisions, and they should never be used routinely or because they are easier for the O.R. staff.

An incision like this has far too many implications for maternal health and future pregnancies. Only under special, extreme circumstances should a supraumbilical incision be utilized.


*Images from "Delivery and postpartum concerns in the obese gravida" (Phillips, Obmanagement, Feb 2009), Gunatiake and Perlow 2011, and the Tixier 2009 study below.

References

Supraumbilical Incisions

Houston MC and Raynor BD. Postoperative morbidity in the morbidly obese parturient woman: supraumbilical and low transverse abdominal approaches. American Journal of Obstetrics and Gynecology 2000 May;182(5):1033-35. PMID: 10819819

OBJECTIVE: Our purpose was to determine the differences in postoperative morbidity in obese women who had a supraumbilical or a Pfannenstiel incision at cesarean delivery. STUDY DESIGN: A case-control retrospective review was conducted of all patients who were at greater than 150% ideal body weight when undergoing cesarean delivery between 1989 and 1995 by means of either a supraumbilical or a Pfannenstiel incision. Patients were excluded if medical records were unavailable. A total of 15 women who had a supraumbilical incision and 54 who had a low transverse incision were included in the analysis. Antenatal complications were examined, as were age, weight, and training level of the surgeon. Postoperative complications were then compared. RESULTS: The groups were similar in age and antepartum complications. However, mean weight and percentage of ideal body weight in the supraumbilical group were both higher (P less than .00001 and P less than .0001, respectively), with the supraumbilical group 83 lb heavier on average. No significant differences were seen in any postoperative complication. CONCLUSION: Postoperative morbidity in morbidly obese women undergoing cesarean delivery does not differ between a supraumbilical approach and the low transverse abdominal incision.

Tixier H et al. Cesarean section in morbidly obese women: supra or subumbilical transverse incision? Acta Obstetrecia et Gynecologica Scandanavica 2009;88(9):1049-52. PMID: 19639463

The obstetrician is more and more frequently faced with the decision to perform a cesarean section in obese women. We describe a technique of supra or subumbilical transverse cesarean section (depending on the height of the projection of the upper edge of the pubic symphysis) specifically designed for morbidly obese women with a voluminous panniculus. We evaluated feasibility and associated morbidity in a retrospective descriptive series of 18 patients operated between 2003 and 2008. We assessed the quality of access to the lower uterine segment and facility to extract the fetus. The mean body mass index was 47.7 kg/m(2) (range 40.1-60.8). The incision was subumbilical in 13 women (72.2%) and supraumbilical in 27.7%. With this technique, the exposition, the section of the lower uterine segment, and extraction of the baby are simple. It can be easily generalized and quickly learnt.

J Reprod Med. 2007 Mar;52(3):231-4. Cesarean birth in the morbidly obese woman: a report of 3 cases. Porreco RP, et al.  PMID: 17465294

BACKGROUND: Primary and repeat cesarean births are a frequent occurrence among morbidly obese women. Technical difficulties encountered in caring for these patients, coupled with physiologic differences, affect their operative management. CASES: Three morbidly obese women (190-296 kg, body mass index 56.7-93.6) had cesarean births utilizing a supraumbilical incision and internal retention abdominal wall closures. Alternative anesthetic management was required in 2 patients. Bariatric operative and postoperative equipment was required in each case, and varying thromboprophylaxis strategies were employed. CONCLUSION: Careful planning along with appropriate specialty consultation is required for a safe and successful cesarean birth in the morbidly obese woman.

J Obstet Gynaecol. 2002 Nov;22(6):691. 'Classical' caesarean section at or near term in the morbidly obese obstetric patient.  Nicholson SC, Brown AD, MacPherson HM, Liston WA.   PMID: 12554273  [no abstract available]

"Morbidly obese obstetric patients undergoing caesarean section with a large, protruding panniculus present major technical problems to the obstetrician and anaesthetist and significant operative risk to themselves...It is our practice to perform a high transverse abdominal incision, avoiding the subpannicular fold, thereby reducing the risks of wound infection, necrosis, and dehiscence."   

Kmom summary: Case report of 2 cesareans in morbidly obese women (BMI 58 and 70) with a large panniculus.  Surgeons used a high transverse abdominal incision just below the umbilicus.  The lower uterine segment could not be accessed, so they did a classical fundal uterine incision.  They briefly discussed alternatives to this subumbilical transverse incision, including supraumbilical midline incisions and a panniculectomy (surgical removal of the pannus, which can be associated with many complications) before the cesarean.  They completely dismissed the fact that low transverse incisions have been used successfully on women of this size in the past.

Successful Low Transverse Incisions Used on Supersized Women

Obstet Gynecol. 1978 Apr;51(4):509-10. Cesarean section in the massively obese. Ahern JK, Goodlin RC.   PMID: 662236

"The case histories of 4 massively obese patients who underwent cesarean section are summarized. In all, a Pfannenstiel incision was made beneath the patient's huge panniculus, and a lower segment cesarean section was easily accomplished. There were no postoperative wound infections and all of the women had an essentially benign postoperative course." 

Kmom Summary: Case report of 4 women who each weighed more than 400 lbs. and were delivered via a Pfannenstiel cesarean incision underneath the panniculus.  The surgeons were surprised by the ease of delivery ("no more difficult than in women of only half their weight") and felt that the Pfannenstiel/low transverse incision was the reason for their good outcomes. They disagreed with earlier statements by other authors that "only a novice" makes a transverse incision under the panniculus.

Anaesth Intensive Care. 1999 Apr;27(2):216-9. Anaesthesia for LSCS in a morbidly obese patient. Patel J. PMID: 10212725

Kmom Summary: The management of a morbidly obese parturient with a body mass index of 88 is reported. She developed asthma during the pregnancy. Lumbar epidural anaesthesia was successfully used for an elective caesarean section and tubal ligation.  Special note: A lower-uterine segment Pfannestiel incision was used with NO problems or infection in this woman who was nearly 500 lbs. at the time of her cesarean.

N Am J Med Sci. 2012 Jan;4(1):13-8. Cesarean section in morbidly obese parturients: practical implications and complications. Machado LS. PMID: 22393542

...A Medline search was conducted to review the recent relevant articles in english literature on cesarean section in morbidly obese women. The types of incisions and techniques used during cesarean delivery, intra-operative and postpartum complications, anesthetic and logistical issues, maternal morbidity and mortality were reviewed. Morbidly obese women with a body mass index (BMI >40 kg/m(2) are at increased risk of pregnancy complications and a significantly increased rate of cesarean delivery. Low transverse skin incisions and transverse uterine incisions are definitely superior and must be the first option. Closure of the subcutaneous layer is recommended, but the placement of subcutaneous drains remains controversial. Thromboprophylaxis adjusted to body weight and prophylactic antibiotics help in reducing postpartum morbidity....

Retracting the Panniculus for a Low Transverse Incision

J Am Coll Surg. 2001 Oct;193(4):458-61. Caesarean delivery and celiotomy using panniculus retraction in the morbidly obese patient. Thornton YS.   PMID: 11584977   [no abstract available]

Kmom Summary: Case series of successful low transverse incisions in 47 morbidly obese pregnant women and 9 obese gynecologic patients, all of whom weighed between 208 to 500 lbs, with BMIs between 33.8 to 76.4.  Shows in pictures their technique of using cloth tape across the abdomen and from both sides of the lower abdomen to the upper body (described as the "suspender" method) to pull the panniculus towards the head and expose the lower uterine segment so that a classical vertical or supraumbilical approach was not needed.  They noted that this technique used materials on hand at most hospitals (instead of specialized bariatric instruments), gave "excellent exposure of the operative field without piercing the skin," and took away the need for a surgical assistant to constantly hold back the panniculus during the operation. Despite the incision being in the "moist subpannicular fold" so vilified in the literature, there were NO wound infections or dehiscences, even in the most obese patients.

MedGenMed. 2006 Feb 21;8(1):52. Preventing a surgical complication during cesarean delivery in a morbidly obese patient: a simple apparatus to retract the abdominal panniculus. Viegas CM, Viegas OA.   PMID: 16915182   Free full text here (includes illustrations not for the faint of heart).

"This case report highlights an unusual intraoperative complication that has medical and medico-legal implications. A simple apparatus designed to retract the panniculus of an obese patient might reduce complications when performing abdominal surgery in such cases." 

Kmom Summary: Case report of a cesarean performed on a morbidly obese mother (BMI 54) who was also a very heavy smoker (which impedes healing).  They induced labor by breaking her waters, but as a result, the baby presented in a brow position and developed fetal distress during the prolonged induced labor.  An urgent cesarean was performed under general anesthesia.  A medical student was drafted to manually hold back the large panniculus during the cesarean.  Her incision healed up well afterwards, but the patient developed severe ulcers at the pressure points where the medical student held back her belly (picture available at the full text site; it's very graphic, be warned).  In response to this case, the authors invented a special apparatus to hold back the panniculus in heavy women during cesareans, using a bar over the surgical bed, chains hooked to the bar and then connected to a Doyen's Retractor, which is used to hold back the panniculus. A picture of this device is available in the article.  The authors state they've used it successfully with no problems since, but do not present any data on this claim.  

Risks of Classical Cesareans 

Obstet Gynecol. 2002 Oct;100(4):633-7. Maternal and perinatal morbidity associated with classic and inverted T cesarean incisions. Patterson LS, O'Connell CM, Baskett TF.  PMID: 12383525

OBJECTIVE: To estimate the maternal and perinatal morbidity associated with cesarean delivery involving the upper uterine segment compared with that of low transverse cesarean delivery. METHODS: A 19-year review of a perinatal database and the relevant charts was used to determine the maternal and perinatal morbidity associated with low transverse cesarean, classic cesarean, and inverted "T" cesarean deliveries. RESULTS:Over the 19 years, 1980-1998, there were 19,726 cesarean deliveries: low transverse cesarean, 19,422 (98.5%); classic cesarean, 221 (1.1%); and inverted T cesarean, 83 (0.4%). As a proportion of all cesarean deliveries, the rates of low transverse cesarean and classic cesarean have remained stable, whereas the rate of inverted T cesarean has risen from 0.2% to 0.9%. Maternal morbidity (puerperal infection, blood transfusion, hysterectomy, intensive care unit admission, death) and perinatal morbidity (stillborn fetus, neonatal death, 5 minute Apgar less than 7, intensive care) were significantly higher in classic cesarean compared to low transverse cesarean. Some maternal morbidity (puerperal infection, blood transfusion) and perinatal morbidity (5 minute Apgar less than 7, intensive care) were also significantly higher for inverted T cesarean compared to low transverse cesarean. CONCLUSION: Classic cesarean section has a higher maternal and perinatal morbidity than inverted T cesarean and much higher than low transverse cesarean. There is no increased maternal or perinatal morbidity if an attempted low transverse incision has to be converted to an inverted "T" incision compared to performing a classic cesarean section.

Am J Perinatol. 2010 Nov;27(10):791-6. Epub 2010 May 10. Maternal and neonatal outcomes of repeat cesarean delivery in women with a prior classical versus low transverse uterine incision. Bakhshi T, et al.  PMID: 20458666

We compared maternal and neonatal outcomes following repeat cesarean delivery (CD) of women with a prior classical CD with those with a prior low transverse CD. The Maternal Fetal Medicine Units Network Cesarean Delivery Registry was used to identify women with one previous CD who underwent an elective repeat CD prior to the onset of labor at ≥36 weeks. Outcomes were compared between women with a previous classical CD and those with a prior low transverse CD. Of the 7936 women who met study criteria, 122 had a prior classical CD. Women with a prior classical CD had a higher rate of classical uterine incision at repeat CD (12.73% versus 0.59%; P < 0.001), had longer total operative time and hospital stay, and had higher intensive care unit admission. Uterine dehiscence was more frequent in women with a prior classical CD (2.46% versus 0.27%, odds ratio 9.35, 95% confidence interval 1.76 to 31.93). After adjusting for confounding factors, there were no statistical differences in major maternal or neonatal morbidities between groups. Uterine dehiscence was present at repeat CD in 2.46% of women with a prior classical CD. However, major maternal morbidities were similar to those with a prior low transverse CD.

Lowering the Risk for Surgical Site Infections in Fat Folk

Image from Chopra 2010 study, link below

We've discussed prevention of surgical site infections before, often in the context of cesareans, but most recently in the context of Emergency Room visits.

Regardless of type of operation, however, accumulating evidence suggests that antibiotic regimens for "obese" people need to be adjusted.

We in the Size Acceptance Movement have been saying for years that people of size often benefit from larger or weight-based dosing for certain types of antibiotics, longer courses of antibiotics in some cases, and IV antibiotics instead of oral antibiotics for serious infections.

This was based on the anecdotal experiences of many people of size over the years, and as such, was summarily dismissed by many in the medical community.

Here is research that confirms the importance of longer courses of antibiotics and weight-based dosing, and which also suggests that more frequent dosing, administration of antibiotics by IV, and perhaps topical infusion of antibiotics into the wound  itself before closing (instead of just systemically in the IV) seem to improve outcomes.

Of course, different types of antibiotics work differently in the system. This means that some types of antibiotics need different dosing for obese people and some don't.  That's important to remember ─ the need for weight-based dosing is not universal for all drugs.  And to be fair to doctors, research has been slow to differentiate these and to provide easy-to-use guidance to doctors in their prescriptions.

Yet there is some research that addresses this issue now, but as we saw recently in the Emergency Room study, getting doctors to follow this research is difficult. In that study, simple guidelines for dosing for high-BMI patients in the E.R. were readily available, but even so, less than 5% of morbidly obese patients received the proper initial dosage of common antibiotics. And that was at a medical center that specialized in treating obese patients!

Furthermore, another study has shown that hospital pharmacists often do not catch/correct underdosing errors in high-BMI patients.  In that study, less than 1/3 of obese patients received an adequate initial dose of vancomycin, only 1% received the optimum recommended dose, and only about 3% of these underdosing cases were caught and corrected by hospital pharmacists.

Far too often, people of size are still being treated with standard antibiotic dosages instead of dosages tailored to their weight, or antibiotics given too infrequently, orally, or for an insufficient length of time.

When will doctors listen to people of size and learn from our experiences?  Heck, when will they learn from their own research?

What is the barrier to adopting these new regimens?  Why aren't they being utilized far more often?  Why aren't hospital pharmacists or medical supervisors catching more inadequate dosing and raising red flags about it?

It's frustrating that this topic is only now being researched and that many hospitals ─ even those that specialize in treating obese patients ─ have been slow to utilize the new dosing guidelines that do exist.

As people of size, we need to be our own best advocates, both before surgery and when surgical site infections occur, so don't be afraid to bring up this concern with your surgeon, or to ask for a consult with an infectious specialist.  Even with a specialist, you may have to be ready to assertively argue your case, but they are more likely to be responsive to advocacy if you can cite research like the studies below.

Providers, please press hard for more research on the most optimal antibiotic dose and regimens, and press vigorously for more caregiver education about and usage of these regimens.  If there is any question about optimal dosage, please take the time to research the issue, and don't be afraid to explore using a different timing or delivery system.  It could literally be the difference between life and death for some people of size.

Infections can be a significant problem in high-BMI patients. Part of this is because of physiological differences like decreased vascular perfusion in fat tissue, and thus decreased oxygenation.  But an under-recognized part of it is because clinicians are using the wrong dosages and treatment regimens for fat folk.

The most efficient approach to improving outcome in obese patients is still to prevent infection in the first place by using the most effective antibiotic dose and treatment protocols available for our unique needs.


References

Am J Obstet Gynecol. 2010 Mar;202(3):306.e1-9. Extended antibiotic prophylaxis for prevention of surgical-site infections in morbidly obese women who undergo combined hysterectomy and medically indicated panniculectomy: a cohort study. El-Nashar SA, et al.   PMID: 20207249

OBJECTIVE: The purpose of this study was to compare surgical-site infection rates in obese women who had extended prophylactic antibiotic (EPA) vs standard prophylactic antibiotic.
STUDY DESIGN: An electronic records-linkage system identified 145 obese women (body mass index, >30 kg/m(2)) who underwent combined hysterectomy and panniculectomy from January 1, 2005, through December 31, 2008. The EPA cohort received standard antibiotics (cefazolin, 2 g) and continued oral antibiotic (ciprofloxacin) until removal of drains. Regression models were used to adjust for known confounders. RESULTS:The mean age was 56.0 + or - 12.1 years, and mean body mass index was 42.6 + or - 8.4 kg/m(2) (range, 30-86.4 kg/m(2)). The EPA cohort experienced fewer surgical-site infections (6 [5.9%] vs 12 [27.9%]; P less than .001; adjusted odds ratio, 0.16; 95% confidence interval, 0.04-0.51; P less than .001), had lower probability of incision and drainage (3 [2.9%] vs 5 [11.6%]; P = .05), and required fewer infection-related admissions (5 [4.9%] vs 6 [13.9%]; P = .08). CONCLUSION: Extended antibiotic prophylaxis can reduce surgical-site infections in obese women after combined hysterectomy and panniculectomy.

Surg Infect (Larchmt). 2009 Feb;10(1):53-7. Prevention of surgical site infections by an infusion of topical antibiotics in morbidly obese patients. Alexander JW, Rahn R, Goodman HR.  PMID: 19245364 

BACKGROUND: The reported incidence of surgical site infection after abdominal surgery in morbidly obese patients is high (about 15% in most studies), and this is associated with considerable disability and an increased economic burden. Topical antibiotics may reduce the incidence of serious infections. METHODS: Standard techniques for the prevention of surgical site infections were used along with the introduction of kanamycin into the subcutaneous space of morbidly obese patients at the time of closure and allowing it to dwell for 2 h. Eight hundred thirty-seven evaluable patients were followed for the development of site complications for at least six weeks postoperatively. RESULTS: One of the 65 patients with a revisional procedure had a primary deep incisional surgical site infection, as did one of the 772 patients with a primary operation. Secondary deep incisional surgical site infections occurred in four patients, two after spontaneous evacuation of a seroma, one from excessive superficial contamination, and one following separation of a nonhealing surgical site. Additionally, 21 patients had minor surgical site complications including incisional separation and stitch-related infections, which required no significant expenditure of resources. CONCLUSIONS: Prolonged contact (2 h) of topical kanamycin solution with the surgical site greatly reduces the incidence of primary infections in the deep subcutaneous space of laparotomy sites in morbidly obese patients.

Expert Rev Pharmacoecon Outcomes Res. 2010 Jun;10(3):317-28. Preventing surgical site infections after bariatric surgery: value of perioperative antibiotic regimens. Chopra T, et al.   PMID: 20545596    Full free text available here.

Kmom Summary: This paper reviews the surgical site infections (SSIs) that occur post bariatric surgery, and how to prevent SSIs. "This paper sets out to define different types of SSIs that occur following bariatric surgery and to discuss existing literature on the critical aspects of SSI prevention and the appropriate use of surgical antimicrobial prophylaxis for bariatric surgery."   

Important quote: "Most antimicrobial agents do not achieve optimal serum levels when administered orally. Although certain oral antimicrobials have comparable bioavailability with their intravenous formulation, the time to achieve maximum serum concentration is slower due to the need for absorption through the gastrointestinal tract. Intravenous antimicrobial prophylaxis is the most extensively studied route and remains the preferred route of administration."

Obes Surg. 2012 Mar;22(3):465-71. Cefepime dosing in the morbidly obese patient population. Rich BS, et al.  PMID: 22249886

Proper dosing of specific antibiotics in morbidly obese patients has been studied inadequately. However, these data are beneficial as this patient population is at an increased risk to develop postoperative infections. Cefepime is an antibiotic used for the treatment of both gram-positive and especially gram-negative infections; administration of the appropriate dose in the morbidly obese population is crucial. We therefore examined the pharmacokinetics of cefepime in patients with body mass index >40 kg/m(2). Ten morbidly obese patients, with a mean [±SD] estimated glomerular filtration rate of 108.4 ± 34.6 mL/min, undergoing elective weight loss surgical procedures were administered cefepime in addition to standard prophylactic cefazolin and studied. Serial serum cefepime concentrations were analyzed after dosing using a validated high performance liquid chromatography method. Pharmacokinetics and duration above the minimum inhibitory concentration (MIC) were determined using a protein binding value of 15% and a MIC threshold of 8 μg/mL. Mean free cefepime concentrations for t = 30, 120, and 360 min were 69.6, 31.6, and 9.2 μg/mL, respectively. The dosing interval was calculated to maintain the free concentration above the MIC (fT > MIC) for 60% of the interval. This was determined to be 10.12 h, including time for infusion. There was no toxicity. Based on this analysis, an increased dose of 2 g every 8 h is necessary to maintain an adequate fT > MIC throughout the dosing interval. Further studies are necessary to determine the efficacy of this regimen in the settings of active infections and critical illness.

Pharmacotherapy. 2007 Aug;27(8):1081-91.  Antimicrobial dosing considerations in obese adult patients. Pai MP, Bearden DT.    PMID: 17655508

As obesity continues to increase in prevalence throughout the world, it becomes important to explore the effects that obesity has on antimicrobial disposition. Physiologic changes in obesity can alter both the volume of distribution and clearance of many commonly used antimicrobials. These changes often present challenges such as estimation of creatinine clearance to predict drug clearance.

Although these physiologic changes are increasingly being characterized, few studies assessing alterations in tissue drug distribution and the effects of obesity on antimicrobial pharmacokinetics have been published. The available data are most plentiful for antibiotics that historically have included clinical therapeutic drug monitoring.

These data suggest that dosing of vancomycin and aminoglycosides be based on total body weight and adjusted body weight, respectively. Obese patients may require larger doses of beta-lactams to achieve similar concentrations as those of patients who are not obese. Fluoroquinolone pharmacokinetics are variably altered by obesity, which prevents a uniform approach. Data on the pharmacokinetics of drugs that have activity against gram-positive organisms-quinupristin-dalfopristin,linezolid, and daptomycin-reveal that they are altered in the presence of obesity, but more data are needed to solidify dosing recommendations. Limited data are available on nonantibacterials. 

An understanding of the physiologic changes in obesity and the available literature on specific antibiotics is valuable in providing a framework for rational selection of dosages in this increasingly common population of obese patients.

Am J Med. 2008 Jun;121(6):515-8.  Multicenter evaluation of vancomycin dosing: emphasis on obesity. Hall RG 2nd, Payne KD, Bain AM, Rahman AP, Nguyen ST, Eaton SA, Busti AJ, Vu SL, Bedimo R.    PMID: 18501233 Full text available here.

BACKGROUND: There is a paucity of data available regarding the dosing of antimicrobials in obesity. However, data are available demonstrating that vancomycin should be dosed on the basis of actual body weight. METHODS: This study was conducted at 2 tertiary care medical centers that did not have pharmacy-guided vancomycin dosing programs or other institutional vancomycin dosing policies or protocols. Patients who received vancomycin between July 1, 2003, and June 30, 2006, were stratified by body mass index and randomly selected from the computer-generated queries. Patients greater or equal to 18 years of age with a creatinine clearance of at least 60 mL/min who received vancomycin for at least 36 hours were included. RESULTS: Data were collected on a random sampling of 421 patients, stratified by body mass index, who met the inclusion criteria. Most patients in each body mass index category received a fixed dose of vancomycin 2 g daily divided into 2 doses (underweight 82%, normal weight 90%, overweight 86%, and obese 91%).  

Adequate initial dosing (greater than or=10 mg/kg/dose) was achieved for 100% of underweight, 99% of normal weight, 93.9% of overweight, and 27.7% of obese patients (P less than .0001).

Ninety-seven percent of underweight, 46% of normal weight, 1% of overweight, and 0.6% of obese patients received greater than or =15 mg/kg/dose recommended by several Infectious Diseases Society of America guidelines.

Pharmacists also failed to correct inadequate dosing because only 3.3% of patients receiving less than 10 mg/kg/dose had their regimen changed in the first 24 hours of therapy.

CONCLUSION: In this multicenter pilot study, obese patients routinely received inadequate empiric vancomycin using a lenient assessment of dosing. Greater efforts should be undertaken to ensure patients receive weight-based dosing because inadequate dosing can lead to subtherapeutic concentrations and potentially worse clinical outcomes.

Eur J Clin Pharmacol. 1998 Oct;54(8):621-5. Vancomycin dosing in morbidly obese patients. Bauer LA, Black DJ, Lill JS.   PMID: 9860149 

OBJECTIVES AND METHODS: Vancomycin hydrochloride dosing requirements in morbidly obese patients with normal renal function were computed to determine the dose of vancomycin necessary to achieve target steady-state peak and trough concentrations and compared with a normal weight population.  RESULTS: Morbidly obese patients [total body weight (TBW) 165 kg, ideal body weight (IBW) 63 kg] required 31.2 mg x kg(-1) x d(-1) TBW or 81.9 mg x kg(-1) x d(-1) IBW to achieve the target concentrations. Normal weight patients (TBW 68.6 kg) required 27.8 mg x kg(-1) x d(-1) to achieve the same concentrations. Because of altered kinetic parameters in the morbidly obese patients (obese: t1/2 = 3.3 h, V = 52 L, CL = 197 ml x min(-1); normal: t1/2=7.2 h, V=46 L, CL=77 ml x min(-1), 20 of 24 patients required q8h dosing (1938 mg q8h) compared with q12h dosing (954 mg q12h) in all normal weight patients in order to avoid trough concentrations that were too low for prolonged periods. There was a good correlation between TBW and CL, but only fair correlation between TBW and V. CONCLUSION: Doses required to achieve desired vancomycin concentrations are similar in morbidly obese and normal weight patients when TBW is used as a dosing weight for the obese (approximately 30 mg x kg(-1) x d(-1)). Shorter dosage intervals may be needed when dosing morbidly obese patients so that steady-state trough concentrations remain above 5 microg x ml(-1) in this population. Because of the large amount of variation in required doses, vancomycin serum concentrations should be obtained in morbidly obese patients to ensure that adequate doses are being administered. Dosage requirements for morbidly obese patients with renal dysfunction require further study.

Surgery. 2004 Oct;136(4):738-47. Perioperative antibiotic prophylaxis in the gastric bypass patient: do we achieve therapeutic levels? Edmiston CE, et al.    PMID: 15467657

BACKGROUND: Perioperative surgical antibiotic prophylaxis requires that therapeutically effective drug concentrations be present in the tissues. METHODS: Patients undergoing Roux-en-Y gastric bypass for morbid obesity were given 2 g cefazolin preoperatively, followed by a second dose at 3 hours. Thirty-eight patients were each assigned to 1 of 3 body mass index (BMI) groups: (A) BMI=40-49 (N = 17); (B) BMI=50-59 (N=11); (C) BMI > or= 60 (N=10). Multiple timed serum (baseline; incision, 15, 30, 60 minutes; prior to second prophylactic dose; and closure) and tissue (skin, subcutaneous fat, and omentum) specimens were collected and cefazolin concentration analyzed by microbiological assay. RESULTS: No significant difference was observed in intraoperative fluid replacement or blood loss among BMI groups. Serum antimicrobial concentrations exceeded resistance breakpoint (32 microg/mL) in 73%, 68%, and 52% of BMI groups A, B, and C, respectively. No significant difference in cefazolin concentration was observed in mean incisional skin and closure tissue specimens in groups A, B, and C. A significant decrease in cefazolin concentration was noted in closure adipose (p=.04), initial (p=.03) and closure omentum (p=.05) tissues in groups B and C compared with A. Over 90% of serum samples exhibited therapeutic concentrations covering 53.8% of gram-positive and 78.6% of gram-negative surgical pathogens. However, therapeutic tissue levels were achieved in only 48.1%, 28.6%, and 10.2% of groups A, B, and C, respectively. CONCLUSIONS: Pharmacokinetic analysis suggests that present dosing strategies may fail to provide adequate perioperative prophylaxis in gastric bypass patients.

Am J Emerg Med. 2011 Dec 12. Underdosing of common antibiotics for obese patients in the ED. Roe JL, Fuentes JM, Mullins ME.  PMID: 22169576

BACKGROUND: Obesity is a growing problem in the United States. Obesity alters the pharmacokinetic profiles of various drugs. Although there are guidelines for dose adjustments for many of the antibiotics commonly used in the emergency department (ED), they are seldom used. METHODS: This is an institutional review board-approved retrospective study at an American Society of Metabolic and Bariatric Surgery Center of Excellence and a level I trauma center with annual ED volumes of more than 80 000 visits. Data were retrospectively collected from ED pharmacy records during a 3-month period in 2008. Any first dose of cefepime, cefazolin, or ciprofloxacin administered in our ED to a patient recorded as both more than 100 kg and with a body mass index greater than 40 kg/m(2) was compared with our hospital guidelines and found to either adhere or not adhere to those guidelines. RESULTS: There were 1910 orders found to meet the study criteria: 775 orders for cefepime, 625 orders for cefazolin, and 510 orders for ciprofloxacin. Adherence rates for first dose of cefepime, cefazolin, and ciprofloxacin administered, respectively, were 8.0%, 3.0%, and 1.2%. CONCLUSION: Emergency physicians frequently underdose cefepime, cefazolin, and ciprofloxacin in obese patients. Underdosing antimicrobials presents risk of treatment failure and may promote antimicrobial resistance. Education is necessary to improve early antibiotic administration to obese patients.