Anamnesis collection and objective examination
The examination must begin with assessing the outcomes of previous pregnancies. If there is a history of fetal demise (antenatal, intranatal, or postnatal), the patient is immediately classified into the high-risk group. It is important to determine the causes of losses: asphyxia, hemolytic disease, malformations, or birth trauma.
During the objective examination, the physician pays attention to basic anthropometric data:
- Height. Women with a height of 150 cm and below often have a contracted pelvis. Excessively tall stature may indicate a male-type pelvis. Any skeletal deformations require attention as they directly affect the bony ring.
- Body weight. Assessed via the body mass index (BMI). Normal values are 18–25 kg/m². Obesity (BMI above 30 kg/m²) of any origin negatively affects gestation and labor.
- Skin and mucous membranes. Pigmentation of the face, nipples, linea alba, and the appearance of striae gravidarum (stretch marks) are considered physiological signs. Pallor, jaundice, cyanosis of the lips, or edema are alarming signs of extragenital pathology. In the presence of pustules or excoriations, the pregnant woman is referred to a dermatovenereologist.
Abdominal inspection and assessment of its shape
In the second half of gestation, visual assessment of the abdomen provides valuable information about fetal position and amniotic fluid volume.
- Ovoid shape: a sign of a physiological course and correct fetal position.
- Spherical abdomen: indicates polyhydramnios, as the uterine dimensions exceed the norm for the given gestational age.
- Transverse oval shape: a typical sign of transverse fetal lie.
- Pendulous abdomen: often found in multiparous women due to diastasis or overstretching of the anterior abdominal wall muscles.
Also, the shape of the abdomen may change specifically in the presence of a contracted pelvis.
Mandatory measurements in the II–III trimesters
At each appointment in the second half of pregnancy, the woman is examined in the supine position. The physician performs two key measurements with a tape measure, the results of which are necessarily compared with gestational norms:
- Abdominal circumference (AC). Measured strictly at the level of the navel. By the end of gestation, this indicator normally should not exceed 100 cm. If AC is greater, it may indicate polyhydramnios, multiple pregnancy, macrosomia, transverse lie, or marked obesity.
- Uterine fundal height (UFH). Measured from the upper edge of the symphysis pubis (pubic symphysis) to the highest point of the uterine fundus. By the time of labor, UFH reaches 35–36 cm. An obstetric caliper may also be used for this measurement.
A critical stage is pelvimetry — determining pelvic dimensions. Since the biomechanics of labor depend on the dimensions of the lesser pelvis and they cannot be measured directly, the physician assesses them indirectly by measuring available parameters of the greater pelvis using an obstetric caliper. Deviations from the norm can lead to significant disruption of the labor course.
Gynecological examination
Bimanual vagino-abdominal examination is the primary method for determining uterine dimensions in the first trimester. It is preceded by an examination in the gynecological chair.
- Examination of external genitalia. With sterile gloves, the physician separates the labia, inspecting the vulva, vaginal introitus, urethra, perineum, and the ducts of the greater vestibular glands.
- Speculum examination. Bivalve, simm's speculums, or elevators are used. A bivalve speculum is inserted closed up to the fornix, then opened. This allows the detection of mucosal cyanosis (a normal sign of pregnancy) or pathological changes.
- Digital vaginal examination. The state of the pelvic floor muscles, extensibility and rugosity of the vaginal walls, fornices, and cervix are assessed. Particular attention is paid to the external os: in nulliparous women, it is pinprick-shaped or round; in multiparous women, it is slit-like (often with scars from past lacerations).
- Bimanual examination. The fingers of one hand are placed in the anterior vaginal fornix, while the other hand gently presses through the abdominal wall. Bringing the hands together, the physician palpates the uterine body (size, shape, consistency, position), then moves to the lateral walls to assess the adnexa and examines the inner surface of the bony pelvis (sacral hollow, lateral walls, symphysis).
Shape of the external cervical os: in nulliparous women — like the letter "O" (round), in multiparous women — like a minus sign "-" (slit-like).
Class and exam questions
How to determine during an examination whether a woman has given birth previously?
The main criterion is the shape of the external cervical os. In nulliparous women, it is round or pinprick-shaped, while in multiparous women, it is slit-like, often with cicatricial changes from past lacerations.
What does a spherical abdominal shape indicate in late gestation?
This shape indicates that the uterine dimensions exceed the gestational norm. Most often, this is characteristic of polyhydramnios.
Why measure the greater pelvis if the fetus passes through the lesser one?
Direct measurement of the lesser pelvis in a living woman is difficult. Therefore, its capacity is judged indirectly — based on the dimensions of the greater pelvis, which are measured with an obstetric caliper.
At what abdominal circumference values should pathology be suspected?
If the abdominal circumference exceeds 100 cm by the end of pregnancy. This may be a sign of polyhydramnios, multiple pregnancy, macrosomia, transverse lie, or obesity.
What else to study on this topic
- Technique of working with the obstetric caliper and main pelvic dimensions
- Algorithm for performing the bimanual vagino-abdominal examination
- Causes and diagnosis of transverse fetal lie
- Influence of skeletal deformations on pelvic structure and labor biomechanics
- Assessment of the adnexa and bony pelvis during bimanual examination
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