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 surg ...
during
labor
Labour or labor may refer to:
* Childbirth, the delivery of a baby
* Labour (human activity), or work
** Manual labour, physical work
** Wage labour, a socioeconomic relationship between a worker and an employer
** Organized labour and the labour ...
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
Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...
.
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
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...
. A low pH and high level of lactate indicate that there is
acidosis
Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma.
The term ''acidemia'' describes ...
, which in turn is associated with
hypoxia.
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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