importance & interpretation of laboratory investigations in obstetric icu by dr shashwat jani

Dr. Shashwat Jani.M. S. ( Obs – Gyn )

Diploma in Advance Laparoscopy.

Consultant Assistant Professor,Smt. N.H.L. Municipal Medical College.

Sheth V. S. General Hospital , Ahmedabad.

Mobile : +91 99099 44160.E-mail : drshashwatjani@gmail.com

Why it’s challenging ???

Care of the critically ill pregnant women presents a unique challenge …

…. Because the assessment, monitoring and the treatment must be taken into an account with maternal physiological adaptations to pregnancy & also the presence of a fetus whose well-being is linked to the mother.

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Leading obstetric causes requiring Obstetric ICU admission …

Pre-eclampsia & Eclampsia

Sepsis

Haemorrhage.

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Conditions which can make pregnant women critically ill….

These wide range of conditions are mainly

divided in to 4 main groups…

1. Specific to pregnancy

2. Increase susceptibility in pregnancy

3. Underlying medical condition

4. Unrelated to pregnancy

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• Specific to pregnancy:

e.g. pre-eclampsia, acute fatty liver, obstetric haemorrhage, amniotic fluid embolism, peripartum cardiomyopathy etc.

• Increased susceptibility in pregnancy:

e.g. venous thromboembolism, aspiration syndromes.

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• Underlying medical condition that is exacerbated by pregnancy:

e.g. congenital heart disease, pulmonary hypertension, and chronic renal failure.

• Unrelated to pregnancy and coincidently developed during pregnancy:

e.g. diabetic ketoacidosis, pneumonia, viral hepatitis and asthma

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To confirm the diagnosis of any condition ...

Clinical examination

Urine Output

Laboratory investigations

Radiologic investigations

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In critically ill obstetric pts…

It’s sometimes difficult to know….

Which Lab. tests are to be done ?

How to interpret these lab. Reports. ?

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Remember

“ During interpretation of laboratory results in critically ill obstetric patients, always consider the normal physiological changes of pregnancy, otherwise underlying disease may be over- or under-diagnosed…!!! “

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Common changes in haematological & biochemical parameters that occur with pregnancy

&

how they impact on maternal / fetalresuscitation…!!!

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Parameter Non-

pregnant

Term pregnancy Impact on resuscitative care

PaO2

(kPa /

mmHg)

13.3 / 100 13.7 / 103 A rightward shift of the maternal

oxyhaemoglobin dissociation curve is a

compensatory mechanism to improve fetal

oxygenation

PaCO2

(kPa /

mmHg)

5.3 / 40 4 / 30 Maintenance of materno-fetal CO2 gradient

is important for ongoing fetal CO2 excretion

HCO3-

(mmol/L/mEq/L)

24 20 ↓ Buffering capacity, acidosis more likely.

pH 7.40 7.44

Haematocrit (%) 37-39 33-35 ↓ Oxygen carrying capacity

White cell count

(n × 109/l)

4 – 11 6 -16 Interpretation of trends in infection more

difficult

Platelet count (n

× 109/l)

150-400 150-400 Gestational thrombocytopaenia is common,

a level <100 × 109/l

warrants investigation

Coagulation

screen

Fibrinogen

levels may

increase up

to 50% at term

PT (Prothrombin time) /aPTT are unchanged

Predominant ↑ in clotting factors and ↓ in

fibrinolytic activity.

Generalised hypercoagulable state

Urea 7.0–21.0

mg/dL

6.7–10.6 mg/dL Seemingly normal renal indices may indicate

renal dysfunction in the parturient

Creatinine 0.7–1.14

mg/dL

0.6–0.8 mg/dL

Liver

function

Tests

Transaminase

levels -

unchanged.

Alkaline

phosphatase

markedly

elevated

Alkaline phosphatase levels increase

throughout pregnancy, initially as a

result of corpus luteal production and

subsequently by the placenta.

Total protein 6.4–8.6 g/dL 4.8–6.4 g/dL Reduction in albumin:globulin ratio, ↑free

fraction of albumin-bound medications

↓ Colloid oncotic pressure

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Now , let’s see …

Interpretation of some most commonly used important

laboratory investigations of Critical obstetric patients…

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Indications Evaluate the cause of certain symptoms such as

fever, bruising, or weight loss Detect anemia Determine the severity of blood loss Diagnose polycythemia vera Diagnose an infection Diagnose diseases of the blood, such as leukemia Monitor the response to some types of drug or

radiation treatment Evaluate abnormal bleeding Screen for abnormal values before surgery

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A hematocrit may be used to:• Identify and evaluate the severity of anemia

(low RBCs, low hemoglobin, low hematocrit) OR Polycythemia (high RBCs, high hemoglobin, high hematocrit)

• Help make decisions about blood transfusions or other treatments if anemia is severe

• Evaluate dehydration & IV Fluid Mx

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Normal = 35 – 45 %

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f

Obstetric Indication

< 8 gm

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Platelets: Risk of Spontaneous Hemorrhage

Count Site> 40,000 Minimal

20-40,000 GI Mucosa

5-20 Skin, Mucus Membranes

< 5 CNS, Lung

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Prothrombin Time ( PT )• Prothrombin time is more sensitive to factor

VII deficiency than factor deficiencies within the final common pathway.

• The prothrombin time has significant interlaboratory variability influenced by the instrument, and more importantly, the reagent used. In an effort to offset variation in thromboplastin reagent, and enhance standardization of PT in patients receiving warfarin, the World Health Organization (WHO) introduced the International normalized ratio (INR).

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• The INR is intended to standardize PT, such that a PT generated from one laboratory would yield an INR value comparable to that generated from any other laboratory in the world.

• INR = [Patient PT/Mean PT] ISI

• Prothrombin time is an important coagulation test because it measures the presence and activity of five different blood clotting factors (factors I, II, V, VII, and X).

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Normal Findings:

• INR : 0.8 – 1.12

• PT : < 15 seconds

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PT increased in• Warfarin use

• Vitamin K deficiency from malnutrition, biliary obstruction, malabsorption syndromes, or use of antibiotics

• Liver disease, due to diminished synthesis of clotting factors

• Deficiency or presence of an inhibitor to factors VII, X, II/prothrombin, V, or fibrinogen

• Disseminated intravascular coagulopathy (DIC)

• Fibrinogen abnormality (eg, hypofibrinogenemia, afibrinogenemia, dysfibrinogenemia)

• Massive blood transfusion due to dilution of plasma clotting proteins

• Hypothermia, as it causes inhibition of a series of enzymatic reactions of the coagulation cascade .

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aPTTTo evaluate bleeding abnormalitiesTo monitor the treatment effects with heparin

• The aPTT is used to evaluate the coagulation factors XII, XI, IX, VIII, X, V, II (prothrombin), and I (fibrinogen) as well as prekallikrein (PK) and high molecular weight kininogen (HK)

• aPTT : 24-35 seconds

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Prolonged aPTT may indicate: • Bleeding disorders

• Use of heparin

• Antiphospholipid antibody (especially lupus anticoagulant, which paradoxically increases propensity to thrombosis)

• Coagulation factor deficiency (e.g. hemophilia)

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PT Result aPTT Result Common Condition PresentProlonged Normal Liver disease, decreased vitamin K,

decreased or defective factor VII

Normal Prolonged Hemophilia A or B (decreased or defective factor VIII or IX) or factor XI deficiency, von Willebrand disease,

factor XII deficiency, or lupus anticoagulant present

Prolonged Prolonged Decreased or defective factor I (fibrinogen), II (prothrombin), V or X,

severe liver disease, disseminated intravascular coagulation (DIC)

Normal Normal orslightly prolonged

May indicate normal hemostasis;

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Bleeding Time ( B T )

• Done to assess platelet function and the body’s ability to form a clot.

• < 7 minutes: Normal

• 8-15 minutes: Platelet dysfunction

• More than 15 minutes: Critical; test must be discontinued and pressure should be applied

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Clotting Time ( C T )

This is a useful bed side test

Take 5ml of blood in a glass tube

If a clot forms in 10 mts & remains firm it is unlikely that the pt has a DIC & also means that the fibrinogen levels are normal.

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Clot retraction time

• Another bed side test wherein the clot retracts at the end of 1 hour.

• This means that the platelets are adequate.

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D - dimer• Used to determine if further testing is necessary to help

diagnose diseases and conditions that cause hypercoagulability, a tendency to clot inappropriately.

• DVT

• Stroke

• Pulmonary embolus

• DIC

Normal Value< 0.5 mg / l OR 0 – 200 microgm / ml

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Positive D –dimer • S /o presence of an abnormally high level of fibrin

degradation products. • It indicates that there may be significant blood clot

(thrombus) formation and breakdown in the body.

• Imp. Conditions Are …- DIC

- Post Surgical- Trauma

- Infection- M.I.

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Fibrinogen Level

• To evaluate fibrinogen, a protein that is essential for blood clot formation.

• When there is an injury and bleeding occurs, the body forms a blood clot through a series of steps.

• In one of the last steps, soluble fibrinogen is converted into insoluble fibrin threads that crosslink together to form a net that stabilizes and adheres at the injury site until the area has healed.

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It is advised in … Unexplained or prolonged bleeding

Thrombosis

An abnormal PT and PTT test result

Has symptoms of or is undergoing treatment for DIC or abnormal fibrinolysis

May have an inherited or acquired coagulation factor (clotting protein) deficiency or dysfunction

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• Normal Fibrinogen Level

= 300 -600 mg/dl.

• More than 150 mg / dL required for coagulation.

• Decrease level found in DIC and Acute Fibrinolysis

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FDP• Normal value : < 10 microgm/dl

Level increses in …. DIC Post fibrinolytic therapy Thromboembolic events Pulmonary embolism Deep vein thrombosis Acute myocardial infarction (first 24-48 h) Preeclampsia Exercise, anxiety, stress, severe liver disease (mild elevation) Acute and chronic renal failure Sepsis/shock Postoperative states Glomerulonephritis Extensive tissue damage

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CRP• Used to detect inflammation

• Normal : 0 – 10 mg / L

Elevated in…• Bacterial infection like Sepsis

• Fungal infection

• PID.

• Chorioamnionitis

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Lab . Criteria for HELLP

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Other tests which are done routinely are….

• Blood Sugar

• Urine R – M ( ketones , sugar, proteins , leukocytes , RBCs )

• Uric Acid

• Culture Sensitivity

• Serum Ammonia level

& many more ….

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