The morphological ultrasound is, together with the ultrasound of the first trimester or week 12, the most important of pregnancy. In it, as its name suggests, the morphology of the fetus and its environment is studied, in order to verify proper development and growth.
When is it performed?
It is performed between 18 and 22 weeks of gestation for several reasons.
- At this age the organs are already formed.
- The relationship between the size of the fetus and the amount of amniotic fluid allows for better visualization.
- If serious pathology is detected, the law prohibits termination of pregnancy beyond the 22nd week (with some exceptions).
How is it performed?
It is performed via the abdominal route, with the woman lying down. Often the vaginal route is also necessary to measure the length of the cervix, see the exact position of the placenta and complete the exploration of the fetal anatomy.
What is it used for?
It is used to analyze in an exhaustive and protocolized way the fetal anatomy in order to detect possible malformations or alterations in the growth of the fetus. In addition, the morphology and implantation of the placenta, the amount of amniotic fluid and the length of the cervix are also studied.
How long does it last?
It will vary depending on the quality of the image that is determined by maternal factors (mainly obesity) and fetal factors (position, amount of amniotic fluid, twin pregnancy …) but on average, the duration will be about 30 minutes.
What is seen in this ultrasound?
As we have said, all parts of the fetus are studied exhaustively, seeing:
- Head: bony and midline integrity, lateral ventricles (choroid plexus), cavum septum pellucidum, thalami, cerebellum, cisterna magna, Sylvian fissure and parieto occipital fissure.
- Face: orbits with crystalline lens, upper lip, profile and nasal bone.
- Neck: exclude masses-liquid collections and nuchal edema.
- Spine: vertebral integrity and alignment and intact skin.
- Chest: lungs symmetrical and homogeneous echogenicity, rule out effusions and tumors, diaphragm intact.
- Heart: regular rhythm, ditus, size, axis, four chambers, outflow tracts, 3VT cut.
- Abdomen: left intra-abdominal stomach (situs), gall bladder, small and large intestine, kidneys and bladder, cord vessels.
- Wall: normal umbilical insertion, with intact wall.
- Limbs: three segments of the four limbs (integrity, alignment and mobility).
- Adnexa: placental location and ultrastructure, cord with 3 vessels, amniotic fluid.
- Cervix: length.
- Uterine arteries Doppler: screening for preeclampsia risk.
Are there any indications before this?
Yes, an early morphological ultrasound (between 15 and 17 weeks) is indicated when an alteration has been detected in the ultrasound or in the first trimester screening or when there is a history of malformations in previous pregnancies.