Estimates of cesarean-related blood loss shown to be too low. (Retrospective Analysis).

PHOENIX, ARIZ, -- Estimates of maternal blood loss during cesarean section are consistently too low, and the greater the blood loss, the greater the inaccuracy according to Dr. Paul R. Shook.

In a retrospective analysis of 440 women who underwent C-sections at Duke University Medical Center in Durham, N.C., Dr. Shook and his colleagues found that blood loss was underestimated by a mean of 500 cc. The disparity became more pronounced as blood loss became greater, so actual losses of about 3,000 cc were underestimated by more than 2,000 cc.

"Our estimates become more inaccurate when it's most important, i.e., when blood loss is greatest," Dr. Shook said at the annual meeting of the Society for Obstetric Anesthesia and Perinatology.

Of most concern is the fact that "the failure to recognize the extent of obstetric hemorrhage may minimize its true importance in maternal morbidity," he said.

Any woman who has hemodynamic compromise and whose estimated blood loss exceeds 800 cc should have her hemarocrit evaluated, because these findings suggest the actual loss is probably much higher, he said.

Using the medical center's obstetric database, the investigators analyzed the records of all women who underwent elective and emergency C-sections from January through August 2002.

Patients who required a perioperative transfusion were excluded, but women of all ages, races, and parities were included. The patients' average age was 28 years and their average weight was 87 kg.