Tuesday, February 17, 2009

Hysterotomy Technique

The classical uterine entry technique during cesarean delivery was a vertical incision, which avoided damage to the vessels laterally and provided ample room for delivery of any fetus in any presentation; but the classical vertical incision was complicated by heavier bleeding from the myometrium and significant risk of extension into the bladder and vagina. Compared to low transverse incisions, it also is accompanied by a significantly higher risk of rupture in future pregnancies. 

In 1882, Kehrer recommeded a low transverse incision at the level of the internal os. Later, Fritsch suggested a transverse fundal incision. Neither of these techniques became popular. Other authors began to suggest a transverse lower uterine segment incision (i.e., Kronig in 1911), but this did not become popular until 1926 when Monro Kerr published the results of his study showing this incision's superiority to the classical technique. 

Since the 1950s, Munro Kerr's low transverse incision has been the standard technique. The incision has typically been made making a small entry with a scalpel and then extending the incision laterally with either sharp or blunt dissection. Various studies have shown the benefit (e.g., less blood loss) of blunt extension of the myotomy instead of sharp dissection (as with bandage scissors). Most techniques involve directing the incision upward to minimize both lateral and downward extension. 

Now comes a study by Cromi et al. (AJOG, 2008;199:292e1-292e6) which randomized blunt extension of the low transverse incision to one of two techniques: either with the fingers separating in a transverse direction (the traditional method) versus cephalad-caudad extension. They found that the new method showed a lower rate of unintended extension (7.4% vs 3.7%, p=0.03) and lower incidence of blood loss > 1500 ml (2.0% vs 0.2%, p=0.4). There was also an increased need for additional stitches in the transverse group (33.2% vs. 22.9%, p=0.001). Other non-significant findings included higher rate of uterine vessel injury in the transverse group, greater estimated blood loss, and larger decrease in hemoglobin.

Many of the techniques used in cesarean delivery are the result of tradition alone. Given how few, good randomized trials exist regarding cesarean technique, this current Italian trial should lead to widespread change of practice until better evidence comes forth. 

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