gynecology and obstetrics
Management of Normal Labor
Admission
Typically, pregnant women are advised to go to the hospital if they believe their membranes have ruptured or if they are experiencing contractions lasting at least 30 seconds and occurring regularly at intervals of about 6 minutes or less. Within an hour after presentation at a hospital, whether a woman is in labor can usually be determined based on the following: Occurrence of regular and sustained painful uterine contractions Bloody show Membrane rupture Complete cervical effacement If these criteria are not met, false labor may be tentatively diagnosed, and the pregnant woman is typically observed for a time and, if labor does not begin within several hours, is sent home. When pregnant women are admitted, their blood pressure, heart and respiratory rates, temperature, and weight are recorded, and presence or absence of edema is noted. A urine specimen is collected for protein and glucose analysis, and blood is drawn for a complete blood count (CBC), blood typing, and antibody screening. If routine laboratory tests were not done during prenatal visits, they should be done; these tests include screening for HIV, hepatitis B, syphilis, and group B streptococcal infection. A physical examination is done. While examining the abdomen, the clinician estimates size, position, and presentation of the fetus, using the Leopold maneuver (see figure Leopold maneuver ). The clinician notes the presence and rate of fetal heart sounds, as well as location for auscultation. Preliminary estimates of the strength, frequency, and duration of contractions are also recorded. A helpful mnemonic device for evaluation is the 3 Ps: Powers (contraction strength, frequency, and duration) Passage (pelvic measurements) Passenger (eg, fetal size, position, heart rate pattern) (A) The uterine fundus is palpated to determine which fetal part occupies the fundus. (B) Each side of the maternal abdomen is palpated to determine which side is fetal spine and which is the extremities. (C) The area above the symphysis pubis is palpated to locate the fetal presenting part and thus determine how far the fetus has descended and whether the fetus is engaged. (D) One hand applies pressure on the fundus while the index finger and thumb of the other hand palpate the presenting part to confirm presentation and engagement. If labor is active and the pregnancy is at term, a clinician examines the vagina with 2 fingers of a gloved hand to evaluate progress of labor. If bleeding (particularly if heavy) is present, the examination is delayed until placental location is confirmed by ultrasonography. If bleeding results from placenta previa, vaginal examination can initiate severe hemorrhage. If labor is not active but membranes are ruptured, a speculum examination is done initially to document cervical dilation and effacement and to estimate station (location of the presenting part); however, digital examinations are delayed until the active phase of labor or problems (eg, decreased fetal heart sounds) occur. If the membranes have ruptured, any fetal meconium (producing greenish-brown discoloration) should be noted because it may be a sign of fetal stress. If labor is preterm (<37 weeks) or has not begun, only a sterile speculum examination should be done, and a culture should be taken for gonococci, chlamydiae, and group B streptococci. Cervical dilationis recorded in centimeters as the diameter of a circle; 10 cm is considered complete. Effacementis estimated in percentages, from zero to 100%. Because effacement involves cervical shortening as well as thinning, it may be recorded in centimeters using the normal, uneffaced average cervical length of 3.5 to 4.0 cm as a guide. Stationis expressed in centimeters above or below the level of the maternal ischial spines. Level with the ischial spines corresponds to 0 station; levels above (+) or below (−) the spines are recorded in cm increments. Fetal lie, position, and presentation are noted. Liedescribes the relationship of the long axis of the fetus to that of the mother (longitudinal, oblique, transverse). Positiondescribes the relationship of the presenting part to the maternal pelvis (eg, occiput left anterior [OLA] for cephalic, sacrum right posterior [SRP] for breech). Presentationdescribes the part of the fetus at the cervical opening (eg, breech, vertex, shoulder). 