Special Feature
Acute Appendicitis Complicating Pregnancy
By Steven G. Gabbe, MD
Acute appendicitis is the most common non-obstetric cause for laparotomy during pregnancy. Despite new imaging techniques, the accurate diagnosis of acute appendicitis remains a challenge, as it has been known for decades that a delay in recognition and treatment may be associated with both fetal and maternal mortality. This review will summarize the past and present literature on acute appendicitis and describe a plan of therapy for these patients.
Acute appendicitis has been consistently observed in between one in 1500 and one in 2000 pregnancies. Pregnancy is not known to increase the occurrence of acute appendicitis that results from obstruction of the appendiceal lumen. Most cases of acute appendicitis occur in the second trimester. The treatment of acute appendicitis during pregnancy is the same as that in the nonpregnant patient, surgical excision by laparotomy or laparoscopy. It is the diagnosis of acute appendicitis that is most challenging. Signs and symptoms and laboratory findings that point to a diagnosis of acute appendicitis may also be associated with normal gestation. Furthermore, there is an understandable reluctance to perform imaging studies or operate unnecessarily on the pregnant patient.
Appendicitis presents most often with abdominal pain and nausea that may or may not be associated with vomiting. During the first two trimesters, abdominal tenderness will be located in the right lower quadrant, but, as the appendix rotates upward during the second half of pregnancy, abdominal pain may be found at the level of the umbilicus or in the right upper quadrant. Right flank pain may occur, suggesting a diagnosis of right pyelonephritis. The apposition of the inflamed appendix to the ureter can also produce pyuria. The laxity of the abdominal muscles and the presence of the uterus may make abdominal tenderness and rebound more difficult to appreciate. Having the patient roll to her left side, while palpating an area of tenderness to the right, may help to differentiate uterine pathology from an inflamed appendix. If the patient rolls to her left side and the pain remains on the right, appendicitis should be suspected. The patient's temperature may remain below 38°C before perforation. The expected leukocytosis of pregnancy can also confuse the diagnosis. It is normal for the white count to reach 16,000/mm3 during gestation, and it may increase further during normal labor. However, a neutrophil count of greater than 80% in the white blood cell differential supports the diagnosis of acute appendicitis, while a white blood cell count persistently below 10,000/mm3 is less likely to be associated with this problem. Ultrasound may be helpful in detecting an appendiceal abscess or stone in the appendix, and CT scanning may also be useful in detecting an appendiceal abscess. Ultrasonography can also be used to rule out other diagnoses, such as an adnexal mass or degenerating myoma.
The differential diagnosis of acute appendicitis includes a large number of non-obstetric and gynecological conditions, including pyelonephritis, the most commonly suspected disorder, nephrolithiasis, cholecystitis, pancreatitis, gastroenteritis, and bowel obstruction. Obstetric and gynecologic conditions that may mimic acute appendicitis include, in late pregnancy, chorioamnionitis, premature labor, placental abruption, and, in early pregnancy, an ectopic gestation, adnexal torsion, and degeneration of a myoma. In most series, a normal appendix is found at laparatomy in 15-20% percent of cases. In pregnancy, a higher negative laparotomy rate is acceptable given the significant consequences of delay and appendiceal perforation. Most studies have shown that the fetal loss rate of 3-5% increases several-fold with generalized peritonitis and perforation. While maternal mortality is rare today, maternal death has been associated with perforation of the appendix.
When performing an appendectomy during pregnancy, it is important to maintain the patient in a left lateral tilt position to maintain uterine blood flow and reduce the risk of supine hypotension. The patient should be well-hydrated with lactated Ringer's solution, and nasogastric suction should be placed. Broad spectrum antibiotics should be administered. In the first trimester, a muscle-splitting McBurney incision over the point of maximal tenderness is preferred. Later in gestation, a right paramedian incision is best. Cunningham and McCubbin have advocated a low midline incision that allows adequate exposure not only for the removal of the appendix, but permits treatment of other diagnoses such as adnexal pathology.1 They emphasize, and others agree, that an appendix that does not appear to be inflamed at laparotomy should be, nevertheless, removed. Laparoscopic appendectomy has also been performed successfully in the first and early second trimesters. Should a laboring patient present with suspected acute appendicitis, a laparotomy and appendectomy should be done. Cesarian delivery is used only for obstetrical indications.
Most recently, de Veciana and colleagues performed a case-controlled study of 49 patients with appendicitis during pregnancy, including nine who suffered pulmonary complications (2 with adult respiratory distress syndrome and 7 with pulmonary infiltrates or edema).2 They concluded that pulmonary injury was increased in pregnant patients with appendicitis who had fluid overload of 4 L or greater, maximum respiratory rate of more than 24 breaths/min, maximum heart rate of more than 110 beats per minute, maximum temperature of 100.4°F or higher, general anesthesia, and tocolytic treatment. Tocolytic therapy for preterm labor included magnesium sulphate, terbutaline, and indomethacin, but indomethacin was most often associated with pulmonary complications. Clearly, tocolytics should be used with caution in patients thought to have acute appendicitis.
References
1. Cunningham FG, McCubbin JH. Obstet Gynecol 1975; 45:415-420.
2. de Veciana M, et al. Am J Obstet Gynecol 1994; 171:1008-1013.
3. Firstenberg MS, Malangoni MA. Gastroentrol Clin North Am 1998;27:73-88.
4. Mahmoodian S. South Med J 1992;85:19-24.
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