Premature rupture of membranes
Premature rupture of membranes: Excerpt from Professional Guide to Diseases (Eighth Edition)
Premature rupture of membranes (PROM) is a spontaneous break or tear in the amniochorial sac before onset of regular contractions, resulting in progressive cervical dilation. Labor usually starts within 24 hours; more than 80% of these neonates are mature. The latent period (between membrane rupture and onset of labor) is generally brief when the membranes rupture near term; when the neonate is premature, this period is prolonged, which increases the risk of mortality from maternal infection (amnionitis, endometritis), fetal infection (pneumonia, septicemia), and prematurity.
Causes and incidence
Although the cause of PROM is unknown, malpresentation and contracted pelvis commonly accompany the rupture. Predisposing factors may include:
❑ poor nutrition and hygiene, and lack of proper prenatal care
❑ incompetent cervix (perhaps as a result of abortions)
❑ increased intrauterine tension due to hydramnios or multiple pregnancies
❑ defects in the amniochorial membranes’ tensile strength
❑ uterine infection.
PROM occurs in nearly 10% of all pregnancies over 20 weeks’ gestation.
Signs and symptoms
Typically, PROM causes blood-tinged amniotic fluid containing vernix particles to gush or leak from the vagina. Maternal fever, fetal tachycardia, and foul-smelling vaginal discharge indicate infection.
Diagnosis
Characteristic passage of amniotic fluid confirms PROM. Physical examination shows amniotic fluid in the vagina. Examination of this fluid helps determine appropriate management. For example, aerobic and anaerobic cultures and a Gram stain from the cervix reveal pathogenic organisms and indicate uterine or systemic infection.
Confirming diagnosis Alkaline pH of fluid collected from the posterior fornix turns Nitrazine paper deep blue. (The presence of blood can give a false-positive result.) If a smear of fluid is placed on a slide and allowed to dry, it takes on a fernlike pattern due to the high sodium and protein content of amniotic fluid.
Staining the fluid with Nile blue sulfate reveals two categories of cell bodies. Blue-stained bodies represent shed fetal epithelial cells, while orange-stained bodies originate in sebaceous glands. Incidence of prematurity is low when more than 20% of cells stain orange.
Physical examination also determines the presence of multiple pregnancies. Fetal presentation and size should be assessed by abdominal palpation (Leopold’s maneuvers).
Other data determine the fetus’s gestational age:
❑ historical: date of last menstrual period, quickening
❑ physical: initial detection of unamplified fetal heart sound, measurement of fundal height above the symphysis, ultrasound measurements of fetal biparietal diameter
❑ chemical: tests on amniotic fluid, such as the lecithin-sphingomyelin (L/S) ratio (an L/S ratio greater than 2 indicates pulmonary maturity); foam stability (shake test) also indicates fetal pulmonary maturity. Presence of phosphatidylglycerol (PG) in the fluid indicates that respiratory distress is unlikely.
Treatment
Treatment for PROM depends on fetal age and the risk of infection. In a term pregnancy, if spontaneous labor and vaginal delivery aren’t achieved within a relatively short time (usually within 24 hours after the membranes rupture), induction of labor with oxytocin is usually required; if induction fails, cesarean delivery is usually necessary. Cesarean hysterectomy is recommended with gross uterine infection.
Management of a preterm pregnancy of less than 34 weeks is controversial. However, with advances in technology, a conservative approach to PROM has now been proven effective. With a preterm pregnancy of 28 to 34 weeks, treatment includes hospitalization and observation for signs of infection (maternal leukocytosis or fever, and fetal tachycardia) while awaiting fetal maturation. If clinical status suggests infection, baseline cultures and sensitivity tests are appropriate. If these tests confirm infection, labor must be induced, followed by I.V. administration of antibiotics. A culture should also be made of gastric aspirate or a swabbing from the neonate’s ear because antibiotic therapy may be indicated for him as well. At such delivery, have resuscitative equipment available to treat neonatal distress.
Special considerations
❑ Teach the patient in the early stages of pregnancy how to recognize PROM. Make sure she understands that amniotic fluid doesn’t always gush; it may leak slowly.
❑ Stress that the patient must report PROM immediately because prompt treatment may prevent dangerous infection.
❑ Warn the patient not to engage in sexual intercourse or to douche after the membranes rupture.
❑ Before physical examination in suspected PROM, explain all diagnostic tests and clarify any misunderstandings the patient may have. During the examination, stay with the patient and provide reassurance. Such examination requires sterile gloves and sterile lubricating jelly. Don’t use iodophor antiseptic solution, because it discolors Nitrazine paper and makes pH determination impossible.
❑ After the examination, provide proper perineal care. Send fluid samples to the laboratory promptly because bacteriologic studies need immediate evaluation to be valid. If labor starts, observe the mother’s contractions and monitor vital signs every 2 hours. Watch for signs of maternal infection (fever, abdominal tenderness, and changes in amniotic fluid, such as foul odor or purulence) and fetal tachycardia. (Fetal tachycardia may precede maternal fever.) Report such signs immediately.
❑ The L/S ratio isn’t useful if obtained from a vaginal pool of amniotic fluid, because vaginal epithelium secretes lecithin. The PG level is accurate, however.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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