“Obstetric anal sphincter injury: 7 critical questions about care,” by Ranee Thakar, MD, MRCOG, and Abdul H. Sultan, MD, FRCOG (February)
In my opinion, the alleged greater likelihood of anal sphincter tear when forceps are used, compared with the vacuum extractor, does not arise from the instrument itself, but the way it is used—specifically, the injudicious application of traction. Such excess traction is a likely occurrence, particularly in the presence of unrecognized cephalopelvic disproportion, and may be the major risk factor for anal sphincter injury. In fact, because the amount of traction applied can only be measured subjectively, the possibility for excess traction always exists, particularly when forceps are used by the less learned.
To eliminate this risk, scientists are developing an electronically controlled forceps that will make it possible to:
- measure objectively the traction exerted during delivery
- promptly alert the obstetrician when safety limits are exceeded
- generate a hard copy printout of the “pull” to be included in the patient’s hospital medical record.1 The printout can be used for research purposes or, in the event of litigation, as direct evidence that no undue traction was applied.
Incidentally, the authors’ recommendation to resort to the vacuum extractor rather than forceps overlooks the fact that these two instruments are not equivalent and, therefore, cannot be used interchangeably. Forceps are used to actively deliver the baby, i.e., to replace the vis a tergo vacuum extraction is used to augment, not replace, the natural forces of labor.
Nicola Perone, MD
Clinical Professor, Department of Obstetrics, Gynecology, and Reproductive Sciences
University of Texas
Dr. Thakar and Dr. Sultan respond: Use the vacuum extractor until this new device is proven
We appreciate Professor Perone’s interest in our article. The aim of our paper was to provide evidence-based medicine from randomized trials and resort to expert experience only in the absence of such trials.
In principle, electronically controlled forceps appear promising, but until shown to be superior to a vacuum extractor in a randomized controlled trial, the vacuum extractor should be the instrument of choice.