Clinical Pearls & Morning Reports
The differential diagnosis and evaluation of abdominal pain during pregnancy can be complicated because maternal adaptations lead to an insidious presentation of intraabdominal disorders. Read the latest Case Records of the Massachusetts General Hospital here.
Q: In what ways can pregnancy complicate the evaluation of abdominal pain?
A: In pregnant patients, the typical findings associated with peritoneal irritation, such as rebound and guarding, may be delayed by uterine growth and increased abdominal muscular laxity that is mediated by progesterone and relaxin. Furthermore, some laboratory findings that would usually be suggestive of an abdominal emergency, such as leukocytosis with a neutrophil shift and a low blood bicarbonate level indicative of metabolic acidosis, would be considered normal in pregnant patients. Finally, early sepsis and hypovolemia may be difficult to detect in pregnant patients, because such signs are obscured by the increase in maternal cardiac output (from 4 liters to 6 liters) and robust plasma volume expansion (from 1500 ml to 2000 ml) during gestation.
Q: Is the frequency of appendicitis higher among pregnant patients than in the general population?
A: Appendicitis and biliary complications are the most common indications for operative intervention during pregnancy. The frequency of appendicitis is the same among pregnant patients as in the general adult population (1 per 500 to 1000 persons). The risk of biliary complications is higher among pregnant patients than in the general population because of the decreased gallbladder ejection fraction and increased stone formation during pregnancy.
A: Graded-compression ultrasonography has long been considered the preferred initial imaging method for the evaluation of pregnant patients with suspected appendicitis. Test performance, however, is challenging, with high rates of nonvisualization of the appendix. Magnetic resonance imaging (MRI) is advantageous because it has multiplanar capabilities, provides excellent soft-tissue contrast, and does not use ionizing radiation. In pregnant patients, contrast material is not routinely administered during MRI. Some gadolinium-based contrast agents can easily pass through the placenta and enter the fetal circulation. The risk to the fetus remains unknown. Gadolinium is used if it is deemed essential, but it is typically not necessary. For the diagnosis of acute appendicitis in pregnant patients, MRI has a reported sensitivity ranging from 94 to 97% and specificity ranging from 97 to 99%. The American College of Radiology Committee on Appropriateness expert panel on gastrointestinal imaging recommends the use of either MRI of the abdomen and pelvis or ultrasonography for the evaluation of pregnant patients with suspected appendicitis.
A: Current treatment recommendations of the Society of American Gastrointestinal and Endoscopic Surgeons support the use of a laparoscopic approach to appendectomy throughout all trimesters of pregnancy when such an approach is technically feasible. This is in stark contrast to historical recommendations, which supported the use of laparoscopy only until 26 to 28 weeks of gestation because of concerns about uterine injury from trocar placement, technical difficulties, and uterine malperfusion from insufflation. However, as experience has grown from the first reports of successful laparoscopy during pregnancy, the safety of this approach throughout all trimesters has been confirmed.