2nd order laboratory parameters – depending on the results of the medical history, physical examination, etc. – for differential diagnostic workup
- In pregnancy:
- Cytomegalovirus (CMV) antibody detection depending on the stage of pregnancy (see below).
- Amniocentesis (amniocentesis) – for diagnosis or exclusion of congenital (“congenital”) CMV infection: PCR (polymerase chain reaction; polymerase chain reaction) for CMV from amniotic fluid; indications:
- At least 6 weeks after maternal seroconversion; or
- Sonographic suspicion of CMV infection.
A negative PCR for CMV from amniotic fluid has a specificity (probability that actually healthy individuals who do not have the disease in question will also be identified as healthy by the score) of 97-100%.
- Outside pregnancy (see below the topic “Diagnosis of CMV infection outside pregnancy”):
- CMV detection in the blood by polymerase chain reaction (PCR).
- Transbronchial biopsy (removal of a tissue sample from the lung by bronchoscopy/lung endoscopy) for a definite diagnosis of CMV pneumonia; if no biopsy is considered: bronchoalveolar lavage (BAL; also in the course of a bronchoscopy) to confirm the diagnosis
- Exclusion of other infections (see differential diagnoses) by pathogen or antibody detection.
- Small blood count [leukopenia (lack of leukocytes (white blood cells) in the blood)]
- Differential blood count [neutropenia (decrease in neutrophil granulocytes in the blood), atypical lymphocytosis (increased lymphocyte count in the blood), thrombocytopenia (decrease in platelets/platelets)]
- Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH), gamma-glutamyl transferase (γ-GT, gamma-GT; GGT); alkaline phosphatase, bilirubin.
Serological parameters in cytomegalovirus infection
Overview of serological result constellations, their interpretation and significance for the diagnosis of CMV infection during pregnancy. The listed constellations of results apply to the situation of initial testing of a serum sample at the indicated stages of pregnancy. The measures are recommended when backup samples from an earlier stage are not available for testing. If an archived serum sample or a negative CMV IgG result from the previous stage of pregnancy is available, determination of a seroconversion can clarify the infection status and determine the questionable time of primary CMV infection.
| CMV serology – findings | Determination in pregnancy phase | Evaluation, measures | ||
| IgG | IgM | IgG avidity | ||
| negative | negative | – | Trimester 1-3 | Not infected, susceptible (susceptible); hygiene consultation |
| negative | positive | – | Trimester 1-3 | Exclusion of false positive CMV IgM; testing of follow-up serum after 10 days to detect questionable seroconversion. |
| Positive | positive | high | before SSW 16/18 | (I) CMV latency(II) CMV recurrence. |
| positive | positive | high | after SSW 16/18 | CMV primary infection possible, periconceptional or during early pregnancy ultrasound check in pregnant woman, amniocentesis if needed; urine check in newborn |
| Positive | negative | high | before SSW 16/18 | CMV latency |
| positive | negative | high | after SSW 16/18 | (I) CMV latency(II) CMV primary infection, periconceptional or during early pregnancy cannot be excluded with certainty.Ultrasound check in pregnant woman, amniocentesis if necessary; urine check in newborn. |
| Positive | negative/positive | intermediate | trimester 1-3 | No statement possible regarding the time of infection |
| positive | positive | low | Trimester 1-3 | CMV primary infection; additional testing immunoblot: anti-gB IgG absent, broad IgM reactivity (anti-IE1/anti pp150/anti CM2/anti-pp65/anti-gB-IgM) Depending on the stage of pregnancy, investigations to clarify a potential fetal infection, ultrasound checks in the pregnant woman, possibly amniocentesis (SSW 21) and/or urine checks in the newborn are indicated |
Diagnosis of CMV infection outside pregnancy
- CMV detection in blood by polymerase chain reaction (PCR); in addition, at least two of the following criteria should be met:
- Fever > 38 °C for at least two days.
- New weakness/weakness
- Leukopenia (lack of leukocytes (white blood cells) in the blood) or neutropenia (decrease in neutrophil granulocytes in the blood), lymphocytosis (increased lymphocyte count) > 5%.
- Thrombocytopenia (deficiency of platelets (thrombocytes) in the blood) < 100,000/nl
- Dual elevated transaminases (GOT (glutamate oxaloacetate transaminase): ASAT, AST (aspartate aminotransferase) GPT (glutamate pyruvate transaminase): ALAT, ALT (alanine aminotransferase)).
