Fetal scalp blood testing is a technique used in
obstetrics
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a surgi ...
during
labor to confirm whether fetal oxygenation is sufficient.
The procedure can be performed by creating a shallow cut by a
transvaginal
Transvaginal refers to a transluminal procedure through the reproductive tract of the vagina, including:
*Transvaginal oocyte retrieval Transvaginal oocyte retrieval (TVOR), also referred to as oocyte retrieval (OCR), is a technique used in in vi ...
ly inserted
blood lancet
A blood lancet, or simply lancet, is a small medical implement used for capillary blood sampling. A blood lancet, sometimes called a lance, is similar to a scalpel style lancet, but with a double-edged blade and a pointed end. It can even be a ...
, followed by applying a thin pipe to the site that samples blood by
capillary action.
Two constituents that are commonly tested by this method are
pH and
lactate
Lactate may refer to:
* Lactation, the secretion of milk from the mammary glands
* Lactate, the conjugate base of lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with ...
, both being indicators of
acid base homeostasis. A low pH and high level of lactate indicate that there is
acidosis, which in turn is associated with
hypoxia
Hypoxia means a lower than normal level of oxygen, and may refer to:
Reduced or insufficient oxygen
* Hypoxia (environmental), abnormally low oxygen content of the specific environment
* Hypoxia (medical), abnormally low level of oxygen in the tis ...
.
Scalp pH and lactate appear to have the same
sensitivity
Sensitivity may refer to:
Science and technology Natural sciences
* Sensitivity (physiology), the ability of an organism or organ to respond to external stimuli
** Sensory processing sensitivity in humans
* Sensitivity and specificity, statisti ...
in predicting umbilical artery acidemia.
Analysis of pH requires a relatively large amount of blood (30–50 μl), and sampling failure rates of 11–20% have been reported.
[ Analysis of lactate only requires 5 μl of blood.][
]
See also
* Fetal scalp stimulation test
Fetal scalp stimulation test is a diagnostic test used to detect fetal metabolic acidemia. It can be used as a non-invasive alternative to fetal scalp blood testing.
Procedure
A firm digital pressure on head or a gentle pinch of fetal head wi ...
References
Tests during pregnancy
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